1 files changed, 63 insertions, 0 deletions
diff --git a/tran/convolve.alg b/tran/convolve.alg
new file mode 100644
index 0000000..94107b4
--- /dev/null
+++ b/tran/convolve.alg
@@ -0,0 +1,63 @@
+(CONVOLVE-ALG
+(NAME "convolve")
+(SUPPORT-FUNCTIONS "
+void h_reverse(sample_type *h, long len)
+{
+    sample_type temp;
+    int i;
+    
+    for (i = 0; i < len; i++) {
+        temp = h[i];
+        h[i] = h[len - 1];
+        h[len - 1] = temp;
+        len--;
+    }
+}
+")
+
+(ARGUMENTS ("sound_type" "x_snd") ("sound_type" "h_snd") )
+(TABLE "h_snd")
+(START (MIN x_snd))
+(NOT-IN-INNER-LOOP "h_snd")
+(STATE 
+        ("table_type" "table" "sound_to_table(h_snd)")
+        ("sample_type *" "h_buf" "susp->table->samples")
+        ("double" "length_of_h" "susp->table->length")
+        ("long" "h_len" "(long) susp->length_of_h;
+         h_reverse(susp->h_buf, susp->h_len)")
+        ("long" "x_buf_len" "2 * susp->h_len")
+        ("sample_type *" "x_buffer_pointer" 
+         "calloc((2 * (susp->h_len)), sizeof(float))")
+        ("sample_type *" "x_buffer_current" "susp->x_buffer_pointer")  )
+(ALWAYS-SCALE x_snd)
+(TERMINATE (MIN x_snd))
+(LOGICAL-STOP (MIN x_snd))
+(INNER-LOOP-LOCALS 
+  "long i; double sum;")
+(INNER-LOOP "
+        /* see if we've reached end of x_buffer */
+        if ((x_buffer_pointer + x_buf_len) <= (x_buffer_current + h_len)) {
+            /* shift x_buffer from current back to base */
+            for (i = 1; i < h_len; i++) {
+                x_buffer_pointer[i-1] = x_buffer_current[i];
+            }    
+            /* this will be incremented back to x_buffer_pointer below */
+            x_buffer_current = x_buffer_pointer - 1;
+        }
+
+        x_buffer_current++;
+
+        x_buffer_current[h_len - 1] = x_snd;
+
+        sum = 0.0;
+        for (i = 0; i < h_len; i++) {
+            sum += x_buffer_current[i] * h_buf[i];
+        }
+
+        output = (sample_type) sum;
+")
+(CONSTANT "h_buf" "h_len" "x_buf_len" "table")
+(SAMPLE-RATE "x_snd->sr")
+(FINALIZATION "    table_unref(susp->table); 
+    free(susp->x_buffer_pointer);")
+)